package com_djm_2025_05_29;
import java.util.Scanner;
public class Demo3 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        //write your code here......
        double avg = 0.0;
        double sum = 0.0;
        double count = 0.0;

        double tmp = 0.0;

        while (scan.hasNextInt()) {
            tmp = scan.nextInt();

            if (tmp >= 0) {
                sum += tmp;
                count += 1;
            } else {
                break;
            }

        }
        //输出格式为：System.out.println(String.format("%.2f",avg));

        avg = sum / count;

        System.out.println(String.format("%.2f", avg));

    }
}
